Surface magnetism in a chiral d-wave superconductor with hexagonal symmetry

TL;DR

This paper investigates surface magnetism in a chiral d-wave superconductor with hexagonal symmetry, revealing unique surface spin and charge currents and their dependence on surface orientation, with potential material candidates like SrPtAs.

Contribution

It demonstrates the coexistence of spin and charge surface currents in a chiral d-wave superconductor with hexagonal symmetry and analyzes their spatial dependence.

Findings

Surface spin currents arise from spin-orbit coupling in the normal state.

Superconducting state exhibits both spin and charge surface currents.

Surface spin polarization varies between zigzag and armchair surfaces.

Abstract

Surface properties are examined in a chiral d-wave superconductor with hexagonal symmetry, whose one-body Hamiltonian possesses the intrinsic spin-orbit coupling identical to the one characterizing the topological nature of the Kane-Mele honeycomb insulator. In the normal state spin-orbit coupling gives rise to spontaneous surface spin currents, whereas in the superconducting state there exist besides the spin currents also charge surface currents, due to the chiral pairing symmetry. Interestingly, the combination of these two currents results in a surface spin polarization, whose spatial dependence is markedly different on the zigzag and armchair surfaces. We discuss various potential candidate materials, such as SrPtAs, which may exhibit these surface properties.